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The Clarification of Liquids by Filtration

F, the recipient.

The French term, "bain-marie," meaning water-bath, is a corrupted translation, sanctioned by use, of the Latin words balneum maris, sea bath, the ancients expressing, figuratively, water by the sea, in the same way as they indicated by the expression balneum ventres equini, the method of conducting digestions by the heat of stable litter.

On the Clarification of Liquids by Filtration.

THE object of filtration is to clarify liquids, and especially those made without the aid of heat. No better way has been found than to make the liquid pass as often as may be necessary through the pores of some substance sufficiently close or impervious to allow the most fluid portion to run through clear and retain the coarser particles or substances, which occasion the cloudy appearance of the liquid.

The filters in most general use, are made of flannel, felt, Canton flannel, and cotton serge.

The article to be employed should be adapted to the kind of liquid to be purified, for if too coarse a tissue be used, the filtration would be too rapid, and therefore imperfect, while on the other hand it would be exceedingly difficult to filter a liquid, highly charged with sugar, through a fine cloth.

When large quantities of liquids are to be filtered, such as brandy, port wine, bitters, etc., wooden vessels, or old casks are used, in which are arranged, layers of sand, charcoal, or cotton, according to the kind of liquors to be filtered. See preparation and arrangement of filters for brandy, port wine, and bitters, etc., pages Filtering bags and filtering paper for cordials are THE CLARIFICATION OF LIQUIDS BY FINING. 25 noticed in other parts of this work. Agitation or vibration is of great efficacy in quickening percolation, or straining, as it displaces the particles which clog the filter, and opens the pores which have become closed. It is convenient to render the filter self-acting, by accommodating the supply of liquid to the rate of percolation, or trickling, so that the pressure upon the porous surface may be always equally great.

The celerity with which any fluid passes through the filter depends,-1st, upon the porosity of the filtering substance; 2d, upon the pressure exercised upon it; and 3d, upon the extent of the filtering surface. The enlargement of the surface is, generally speaking, the safest and most efficacious plan for increasing the rapidity of filtration, especially for liquids containing much sugar. We will hereafter show that fermented liquors clarify themselves in course of time.

In order, however, to hasten the process of clarification, white of eggs, isinglass, milk, blood, etc., are occasionally used. See "Fining," page 26.

On the Clarification of Liquids by Fining.

GOOD wines, or any fermented liquors, need no artificial "fining," as they always clarify themselves by repose. With those, however, which are "out of condition," or of inferior quality, it is often necessary, as without such a proceeding, they remain unsaleable. The disadvantages resulting from the artificial clarification of fermented liquors are that they do not afterwards "stand well on draught," that much of the conservative astringent matter which they contain is precipitated with the "finings," that their piquancy and flavor is more or less diminished, and that they are more than usually